<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://cdn.bootcdn.net/ajax/libs/vue/2.6.14/vue.js"></script>
</head>
<body>
    <div id="app">
        <!-- <tom @add="$refs.jerryRef.count++"></tom> -->
        <tom @add="$refs.jerryRef.add()"></tom> 
        <jerry ref="jerryRef"></jerry>
    </div>
</body>
<script>
Vue.component('Tom', {
    template: `
        <div>Tom组件<button @click="$emit('add')">+1</button></div>
    `
})   
Vue.component('Jerry', {
    template: `
        <div>Jerry组件-{{count}}</div>
    `,
    data(){
        return {
            count: 0
        }
    },
    methods: {
        add(){
            if(this.count<100){
                this.count++
            }
        }
    },
})    
let vm = new Vue({
    el: '#app',
    data(){
        return {
           
        }
    }
})
</script>
</html>